U.S. Pat. No. 2,661,024 (Knox 1953) is representative of a style of plunger which has been used in gas wells for the last 50 years. The plunger has a tubular body with an exterior surface and an interior flow passage. A number of seals encircle the exterior surface to prevent fluid from passing along the exterior surface of the plunger. A valve member is positioned at the end of the tubular body. The valve member moves axially along the interior flow passage toward a valve seat. The valve has an open position and a closed position. In the open position, the valve is spaced from the valve seat allowing a free flow of fluids along the interior flow passage. In the closed position, the valve member engages the valve seat to prevent fluids from entering the interior flow passage. The valve has a stem which protrudes past an end of the tubular body. When the plunger reaches its receiver at a bottom of the gas well, this stem strikes the receiver and the valve is pushed from the open position to the closed position. When the valve member is closed, gas pressure building below the plunger causes the plunger to rise in the tubing. As the plunger rises, it pushes ahead of it accumulated liquids. Upon reaching the surface, the valve member is moved to the open position by striking the stem which permits gas to pass through the plunger. The plunger valve then descend back into the well, with gas passing through the interior flow passage of the plunger. Upon reaching the bottom of the well, the valve member is moved to the closed position so that gas pressure is allowed to build up again below the plunger.